The present invention relates to swimming shoes intended for breast stroke swimming. Each shoe is provided with two non-symmetrically arranged propulsion surfaces. Such swim shoes are intended to facilitate the forward motion of a swimmer in the water. Simultaneously the shoes shall enable the swimmer to walk on land and also in the water.
German Patent Publication (DAS) No. 1,001,167 describes a swimming shoe which is provided with two flippers. It is also known to provide swim shoes with symmetrically arranged flaps or flippers, whereby these flaps substantially extend in the plane of the bottom wall or sole of the swim shoe when the flaps are fully extended, thereby providing an opening angle of approximately 180.degree. .
U.S. Pat. No. 1,603,616 discloses a swimming appliance in which a paddle type of flipper is hinged to the sole of a boot type swimming shoe. The paddle may be placed into an upright position, thereby enabling the swimmer to walk, whereby the paddle is held in the upright position by a spring hook. The spring hook is adjustable to limit the angular movement of the paddle.
German Patent Publication (DOS) No. 2,009,381 discloses a swimming shoe wherein the flipper forms an integral part of the shoe proper, whereby walking with this type of flipper is substantially impeded.
German Utility Model Application No. 385,699 of May 30, 1964 discloses a flipper type of sandal especially intended for water treading. The hinge is such that a lifting of the legs will cause the paddle type flipper to fold downwardly, whereas a thrusting of the leg downwardly will raise the flipper, thereby increasing the surface area of the sandal.
All types of prior art swim shoes do not provide the desired substantial improvement of the breast stroke type of swimming speed because the sole of these shoes do not extend continuously at a right angle to the direction of the main thrust when the swimmer moves his legs in the breast stroke type of leg movement. Thus, the respective propulsion force is not efficiently utilized because an undesirably large proportion of the propulsion force is diverted, whereby the legs of the swimmer are forced downwardly which further decreases the efficiency of the breast stroke type of movement by increasing the surface area of the swimmer's body relative to the feed advance direction in the water. Thus, prior art swim shoes have largely been ineffective for the breast stroke type of swimming and most prior art swim shoes were primarily designed for the crawl type of swim stroke.
Further, it is intended that the present swim shoe shall enable the user to walk and stand without the need for any manual adjustments. This is not possible with prior art swim shoes if it is simultaneously intended to optomize the effect of the frog kick thrust.